1. Field of the Invention
The present invention relates to a ceramic sprayed member-cleaning method, a program for implementing the method, a storage medium storing the program, and a ceramic sprayed member, and more particularly to a ceramic sprayed member-cleaning method for cleaning ceramic sprayed members, such as an electrode, a focus ring, and an electrostatic chuck, which are used in a chamber in which a plasma atmosphere is formed by a processing gas, and a conveying arm used in a conveyor for conveying substrates and the like to a processing apparatus, a program for implementing the method, a storage medium storing the program, and a ceramic sprayed member.
2. Description of the Related Art
Conventionally, a plasma processing apparatus that carries out predetermined plasma processing on a substrate such as a semiconductor wafer generally includes a chamber for housing the substrate. In such processing apparatus, members with ceramics such as yttrium oxide (Y2O3) (i.e. yttria), or aluminum oxide (Al2O3) thermally sprayed thereon are used as an inner wall of the chamber, an upper electrode and the like. In general, ceramics tend to have high reactivity with water in the air, and therefore, when the chamber is opened to the atmosphere for a periodic inspection or when the chamber is subjected to wet cleaning, a large amount of water can be attached to the inner wall of the chamber, an upper electrode, and the like, which are formed of the ceramic-sprayed members.
Desorption and attachment of water from and to the inner wall of the chamber can cause problems, such as an increase in chamber-evacuating time, which results in lowering of the operation rate of the processing apparatus, abnormal film formation in forming a metal film, instability of the etching rate in etching an oxide film or the like, separation of particles, and abnormal discharge in generating plasma.
To solve such problems, there has been proposed a vacuum chamber as the above-mentioned chamber that is provided with a heater for heating a non-reactive gas, such as argon, to a temperature not lower than a predetermined temperature before the non-reactive gas is introduced into the vacuum chamber, and a chamber heater capable of applying additional heat to the vacuum chamber, whereby impurities or contaminants are scavenged therefrom (see Japanese Laid-Open Patent Publication (Kokai) No. H07-78775).
In this vacuum chamber, after the non-reactive gas heated by the heater is passed through the vacuum chamber over a predetermined time period during a processing operation, the flow of the heated non-reactive gas to the vacuum chamber is stopped, and pressure within the vacuum chamber is checked. Further, the vacuum chamber is evacuated to approximately 6.7×10−5 Pa (5.0×10−7 Torr) while the vacuum chamber is still hot, and if the pressure of the non-reactive gas within the evacuated vacuum chamber is higher than that in the vacuum chamber obtained by a previously carried out test, it is estimated that there is a leak from the vacuum chamber, whereby measures can be taken to solve the problems.
Further, there has been proposed an ECR (Electron Cyclotron Resonance) plasma etching apparatus comprised of a chamber, a microwave-introducing port formed in one end of the chamber, for introducing a microwave into the chamber, an exciting coil disposed in a manner enclosing the microwave-introducing port or a part of the chamber, a gas-introducing system for introducing a predetermined amount of gas into the chamber, and an evacuating system for evacuating the chamber to a high vacuum (see Japanese Laid-Open Patent Publication (Kokai) No. H08-181117).
In this ECR plasma etching apparatus, the chamber is evacuated by the evacuating system at a low rate, Ar gas is introduced into the chamber through the gas-introducing system, and a microwave is supplied via the microwave-introducing port. Further, the exciting coil is energized to thereby generate plasma in the chamber. Contact between the generated plasma and the inner wall surface of the chamber raises the temperature of the inner wall surface of the chamber, whereby water molecules attached to the inner wall surface are vaporized.
Further, there has been proposed an ultrahigh vacuum apparatus comprised of a growth chamber as an airtight container which is evacuated to an ultrahigh vacuum, a substrate manipulator as a member accommodated in the growth chamber, a substrate holder provided at a lower end of the substrate manipulator, and a heater section as internal heating means disposed at opposite sides of the substrate manipulator with respect to the horizontal direction (see Japanese Laid-Open Patent Publication (Kokai) No. 2000-294508).
In this ultrahigh vacuum apparatus, the growth chamber is externally heated while operating a vacuum pump to evacuate the growth chamber to an ultrahigh vacuum, and further the substrate manipulator and the substrate holder are heated by the heater section within the growth chamber while evacuating the growth chamber so as to maintain the ultrahigh vacuum in the growth chamber. Thus, degassing of the growth chamber is carried out.
Further, there has been proposed a plasma processing apparatus comprised of a base member formed therein with an opening, an electrode mounted at the opening from below via an insulating member, a box-shaped lid disposed above the electrode, a vacuum chamber formed as a space enclosed by the lid, the base member, and the electrodes, a heater mounted on an upper surface of the lid, for heating the inner wall of the vacuum chamber, and a control section for controlling the heater (see Japanese Laid-Open Patent Publication (Kokai) No. H11-54484).
In this plasma processing apparatus, when plasma processing is carried out, the heater is controlled by the control section so that the temperature of the inner wall of the vacuum chamber is held within a preset temperature range. This makes it possible not only to reduce the amounts of water and organic substances adsorbed on the inner wall of the vacuum chamber, but also to quickly evaporate off the water and the organic substances. Moreover, time required for vacuum suction can be considerably shortened.
Furthermore, there has been proposed a plasma cleaning apparatus comprised of a vacuum chamber defined by a base plate and a lid, an electrode mounted through the base plate, a replaceable shield member mounted on a ceiling surface within the vacuum chamber, and a control section connected to a vacuum gauge, and having a storage section for storing a set vacuum degree and a set chamber-evacuating time period which are set to the vacuum chamber, and a clock (see Japanese Laid-Open Patent Publication (Kokai) No. H11-54487).
In this plasma cleaning apparatus, the current time t1 is read in from the clock so as to measure the chamber-evacuating time period. Then, vacuum measurement data is delivered from the vacuum gauge, and a time t2 when the degree of vacuum reaches the set vacuum degree is read in. Further, if the chamber-evacuating time period T determined from the time t1 and the time t2 is within the set time period T0, a gas supply device is driven to introduce a gas for plasma generation into the vacuum chamber. Next, a high-frequency power supply is driven to apply a high-frequency voltage to the electrode, whereby plasma is generated for plasma cleaning, and plasma cleaning is thus carried out. As a result, an increase in the evacuation time period can be suppressed to a predetermined limit so as to maintain tact time.
Another apparatus similar to the above described plasma cleaning apparatus has also been proposed (see Japanese Laid-Open Patent Publication (Kokai) No. 2002-124503).
However, in any of the proposed apparatuses, in the case where a member having ceramic thermally sprayed on a surface thereof is used in the chamber, the effect of removing water is limited, so that it is impossible to reliably suppress desorption and attachment of water from and to the ceramic sprayed member.